Invariant
by angellwings
Summary: "The very concept of time travel makes no sense, since time doesn't flow. The fact that we think time passes is just an accident of our nervous systems—of the way things look to us. In reality, time doesn't pass; we pass. Time itself is invariant. It just is." ― Michael Crichton, Timeline.


**A/N:** So I set out to write fluff but then the Angst Brigade started speculating wild possibilities for the finale. We took clues or unresolved threads from previous episodes and tried to analyze how that could be explored. One of the things that came up was Denise's speech to Lucy about how knowing the future gave her hope. Immediately, that gave me an idea. What if Future Lucy came back to save her boys? What if she and Flynn became partners in her journal she lost Wyatt and Rufus? What if someone resolved the overlapping timeline issue in the future and the first thing Lucy decided was that she needed them back? How would that play out? What would that look like? Well, here it is.

I promise you this is not based on Spoilers. I only used what was in the synopsis and the production stills and the promo. (Plus what they've shown in previous episodes.)

Thanks to the girls in the Angst Brigade for the idea! (Even if I wanted to write fluff lol).

Happy reading!

angellwings

* * *

 _Invariant_

 _By angellwings_

* * *

" _The very concept of time travel makes no sense, since time doesn't flow. The fact that we think time passes is just an accident of our nervous systems—of the way things look to us. In reality, time doesn't pass; we pass. Time itself is invariant. It just is."_

― _**Michael Crichton, Timeline**_

* * *

He knew her anywhere - _anywhen_ , even.

There wasn't a time period in which he didn't recognize Lucy Preston. He knew her better in some decades than others, admittedly. (1941 Hollywood was currently springing to mind.) But he always knew her. Even in the hideous Beetlejuice garment she was wearing now. He hated it and yet she still looked stunning while wearing it. How was that possible? He knew her even when 1888 seemed to be burning down all around them.

Bullets, flames, scuffles. Blood, fractures, bruises.

Violence and chaos encircled them.

He kept a tight hold on her arm through all of it, until he hadn't. Until they were jumped from behind and she was suddenly being ripped from his grasp. Not, unfortunately, for the first time since they'd met. This time felt different. Felt final. This time he felt loss. It shocked him and he had no idea where the foreboding sense of dread that threatened to drown him came from.

He fought on auto pilot, keeping an eye on where Lucy was disappearing from view. He could hear her calling for him, but he barely registered his own voice calling for her. The growing distance felt hopeless. In the midst of everything he'd lost recently, _Lucy_ was the beacon of hope. Things were strained between them but one fact stayed constant. One true concept bounced around inside his skull and wouldn't let him go. Wouldn't let him quit.

" _No matter how bad it gets we're together. None of us have anything anymore except each other."_

He heard a crunch and twist as one of the two Rittenhouse hired hands he'd been fighting crumpled at his feet. He didn't even realize his hands had been on the henchman's neck until he heard it snap under his fingers. Oh well, one less obstacle between him and Lucy. One more to go.

A sucker punch to the back of his head sent him stumbling forward. His knees hit the dirt and the world spun. He looked up and found _her_.

But it's a _her_ that he didn't know. No Beetlejuice dress. No attempt to blend in at all, actually. No softness in her expression. No wonder in her eyes. _Hard_. He was reminded of Garcia Flynn and Emma Whitmore. Cold, hard, unshakeable. He could make out sparse strands of grey in her dark locks despite the orange glow of the burning buildings around them and the lines of her face seemed deeper. Trenches of pain and grief and loss.

One thing became clear, _this was not his Lucy_.

She was unrecognizable. Eyes were the same shade of brown. Skin was still creamy and fair. But he did not recognize this woman.

She grabbed his arm and pulled him to his feet. The last of the two Rittenhouse goons that ambushed him rushed forward and without batting an eye she pulled the trigger on his weapon. He didn't even see her holding it. He lost it in the scuffle. She didn't flinch as she took the shot and didn't look affected by the body as it fell. This woman was made of fire and steel and deep pools of rage. She was not to be fucked with.

"We're getting you out of here," she said as her grip on the underside of his arm tightened. These hands were calloused like his. Thin and bony but overworked. Where the hell did she come from?

The shock finally faded and Wyatt found the presence of mind to dig his heels into the dirt.

"Hell, no," he heard himself say firmly. "Not without Lucy."

"You don't have to worry about her. Flynn is already on his way. She'll be fine. _Let's go_ , soldier."

"All due respect, _Ma'am_ ," he said as he dug in deeper. Her eyes flicked to his and in that glance he saw a moment of warmth. A brief bit of affection. "I've left her behind before. _I won't do it again_. Not even for you."

"I am not giving you a choice," she said with a glare. "We're getting you and Rufus to the Lifeboat. We came all this goddamn way and I am _not_ letting you go after her. The very fact that I am _here_ should tell you she will be _fine_. Honestly, you are just as frustrating as I remember. For a highly trained soldier, you always had a surprisingly difficult time following orders."

Remember? _Had_? She was talking about him as if - as if he were dead.

She huffed and tugged at his arm again, but not even an older battle hardened Lucy could move him. His eyes searched her again and this time he saw traces of the woman he currently knew. The woman he was desperate to get back to. Persistence. Resilience. Determination. Trademarks of Lucy Preston if he'd ever known any. How long had it been for her since she'd lost him? What had she become in his absence? How did he make her understand that threat of death would not keep him from getting to Lucy if she needed him? _How did he reach her_?

" _No matter how bad it gets we're together,"_ He told her as he met her fiery glare with his own. "I'm quoting your words. Or do you not remember them?"

"I _said them_ , Logan," she sneered as she released his arm and then stepped as close to him as she could. Chest to chest. Glare to glare. Scowl to scowl. "Of course I remember. But I remember the second half much more vividly. _None of us have anything anymore except each other._ If you go to her then she won't even have that - won't even have _you_. I know what that path looks like and I will not let her lose you _too_. I will not let her become _me_. You want to protect her, Master Sergeant? Protect her from _me_. My life is not one you want her living. My life is no life at all."

He saw sorrow in her glare. Mournful. Heartbroken. Desperate. He'd seen Lucy like this only once before and it had terrified him to his core. She had been ready to make the self sacrificial play to stop Rittenhouse. Suddenly, it was 1918 again and he was looking at Lucy's wild eyes and grappling with the concept of losing her to a world of weapons and espionage. Of losing her before he ever had a chance to tell her the complete and total truth.

The unrecognizable woman in front of him suddenly snapped into focus. The hard lines on her face were no longer foreign. It turned out, he did know this Lucy. He had seen her before.

"I'm not sitting this one out, Lucy," he told her. "You can let me go or you can come with me. But I'm not hiding. I'm not leaving _her_ alone. We've lost everything, even almost lost each other. If you remember anything, remember _that_."

"There's still one more thing she could lose," Lucy told him with a tearful expression. "One she won't rebound from."

"I'm not him. You can make sure I'm not _him_. Help me change your future. _Rewrite it_."

Her watery tired eyes met his before she let out a resigned sigh and nodded. She poked his chest, hard, and gave him a scolding glare. "No cowboy stuff. You hear me?"

"Yes, ma'am."

"I swear to god if I get back to my timeline after this and you are still dead it will be because you are the most hot headed reckless man I have ever met in my life. When I say no cowboy stuff I don't just mean _today_ ," Lucy told him with a huff. "Understand?"

"I got it. No cowboy stuff," Wyatt said with a nod.

They rushed toward where Emma had taken his Lucy in silence. Wyatt watched this new Lucy carefully. She was essentially the same Lucy just...hardened. It broke his heart to see her so cold and detached. Was it really losing him that did this to her? Did her Wyatt die before he had a chance to correct his mistakes? Before he was able to tell her how he felt? Before he apologized for fucking everything up? Was she this way because she never knew?

"So is today where our timeline's go their separate ways?" Wyatt asked. "Do we have the same memories of everything else?"

"Do you mean, did Jessica still magically reappear in our lives?" Lucy asked him in a flat tone. "Yes, she did."

He sighed and closed his eyes for a moment. He still didn't know what to do with Jessica. How could he process the damage he let her do, the way he endangered everyone he cared about, and the bull headed way he reacted to the truth? It was too much for his mind and his heart. He didn't know how to come back from it. How to fix the numerous ways he so completely _fucked up_.

"You did the best you could."

His eyes opened and snapped to the older Lucy's face. "What?"

Her expression looked pinched with pain as she answered him. "They hit you where you were weak. They hit _both_ of us where we were weak. You did what your mind told you was the right thing. Hell, I did what my mind told me was the right thing. The _easiest_ thing. But...we were wrong. Not just you, Wyatt. _We._ It took time and distance from the situation for me to see that you...you reached out for me several times. I did what was obvious. I pushed you toward her because that was what was easiest for _me_. Fighting her memory for you would have been too hard despite actually being what was _right_. You followed my lead and did the same. You didn't fight for me because I didn't fight for you. So you chose the easy obvious answer. You chose _her_. Even when your heart told you that was wrong. It wasn't just you. It was both of us."

"Yeah," he said with a scoff. "But I'm the one who let her into the bunker. _Me."_

Her head tilted and she gave him a small teasing grin. "Yeah, that one was all you. Wasn't it?"

Despite his guilt and the chaos around them, and the bizarre fact that he was talking to someone from the future, he laughed.

"Did he ever tell you?" Wyatt asked as his laughter subsided and his expression sobered. "How he felt?"

If he was about to die, he should probably know how it all went down and whether or not he should do anything differently, right?

"There was never—the timing was never right for us. I think he tried. But no. He never said it. I never got the actual words," Lucy answered as her eyes misted over and her voice filled with emotion. She closed her eyes tight. "I can't be certain of what he felt. I _think_ I know. Because I know how I felt about him but sometimes I wonder...I wonder if I'm comforting myself with a lie." Her eyes opened again as she shook her emotions away and cleared her throat. "It doesn't matter, really. Not anymore. I shouldn't even be telling you this. But that's how it always was with you...I always told you things I'd rather keep to myself. Why would that change after all these years, even if I'm not your Lucy?"

"It matters," he told her as he stopped her with a hand on her arm. " _It matters_."

How could he be this stupid? How could he leave her with any doubts? He should have listened to Rufus and admitted it in goddamn 1918.

"If you were my Lucy at any point then it _matters_. I'm fucked up. I know that. I've made so many mistakes and done unforgivable things. I _hurt_ you and I have no idea what to do about it. I—I have a wife and maybe I have a kid and that very fact messes with my goddamn head and spins everything around. But at the center of all that spinning, the one person that grounds me when I feel like I can't take it anymore, _is Lucy Preston_. I don't even know when or how that happened. It's like I woke up one day and you were _everything_ ," he admitted as he held Future Lucy's intrigued gaze. He needed her to know. He needed to correct the damage he did to her in her timeline. _If nothing else_ , he could do this. She refused to look at him, but he continued anyway.

"But then you were gone and while you were gone those feelings grew until they practically ate me alive. Hell, after 1941 I thought I had everything I never knew I wanted. I had never been that happy in my life. Not even when—not even when things were _good_ with Jess. I was ready to jump head first into a life with you. _I wanted that life to start right then_ ," he assured her. Their brief day of a relationship was burned into his memory. The image of Lucy, creamy skin and soft curves, was seared onto his eyelids. What he could have had all this time haunted him even when he tried to shut it out.

His brow furrowed and he shook his head before speaking again. "But, with Jessica—I still don't know what the fuck would have been the _right_ thing to do. I got lost in my past and my guilt and the guy who drank till he passed out, the guy who spent all his free time pouring over _every shred_ of evidence, and the guy who looked into her cold lifeless eyes after they found her body. That guy was an ass and I tried to let myself fall back into him. But it still wasn't the same. I wasn't the same," he confessed. Lucy saved his life and changed him _for good_. He could never be the man he was before he met her _ever again._ Even if he wanted to, even if that would be easier. He could never go back.

A world without Lucy Preston was not an option and he refused to remember his shell of a life before that waiting room at Mason Industries. He would never go back to that half asleep drunk jackass he used to be. "I wasn't just the grieving soldier anymore. No, I was - _am -_ the man who loves Lucy Preston and sometimes I think I'm the only person on the planet who really sees how impressive she is. She sure as hell doesn't see it. Lucy made me the best version of myself, but the _worst_ version of myself has scarred her in ways I never intended. I don't see how I can come back from that. I love her - _you -_ but I'm afraid I've lost you for good."

The older Lucy, who had been nothing but steel and fire since she suddenly appeared in front of him, was crying. Tears were flowing down her cheeks. She looked near joyful and so much like his Lucy that he half expected her to launch herself at him in a hug.

Instead she wiped her eyes, sniffled, and then said, "Thank you. You have no idea how much I - just _thank you_." Her teary disposition vanished as quickly as it came and as soon as it was gone she was smacking his arm repeatedly in exasperation. "But don't tell me. _Tell her_. Idiot."

He flinched away from her. She had a point but _damn_ , that actually hurt. "Ow, _ow,_ okay!"

Gunshots rang out somewhere ahead of them and fear filled him. He looked over at Lucy and saw the recognition on her face.

"Don't worry. Those bullets weren't for your Lucy," she told him with a thick swallow before she took off toward the sound.

He ran after her, still trying to process her words, and what they found when they reached the alley where the gunshot came from enraged and terrified him all at once. Carol Preston and Nicholas Keynes were dead. And Emma had _his_ Lucy by the throat. Lucy's face was beaten to hell and his chest ached at the sight of her bloodshot eyes. She had a busted lip, a cut over her brow, and a nasty black eye. Her face was nearly purple from lack of air. Her eyes connected with Wyatt's and he felt every bit of her pain. Emotional and physical.

He glanced over at Future Lucy and saw her shaking her head and glancing around like something was wrong. She seemed stunned. Frozen in place. But they didn't have time for that.

Wyatt barreled toward Emma, knocked her to the ground, and then pinned her underneath him. Emma found leverage somehow, though, and shoved him off of her. She reached for her weapon and Wyatt kicked it away. That's when she pulled the knife from somewhere in the folds of her dress. He ducked and dodged and deflected but Emma was skilled and always back for another attempt. Unless he could rip that knife from her hands, odds were good she'd stab him eventually. He needed something to give him the upper hand. If she took him out then Lucy, both Lucys, were next. Without Flynn here to back him up, he was certain of that.

His eyes landed on Emma's gun. His was in the hands of a shellshocked time traveler so that seemed to be his only option. Releasing Emma to reach for it though was likely a risk that was going to get him killed. Was this the moment that created the hardened Lucy standing next or his Lucy? He flicked his eyes to both of them and noticed the older Lucy had stepped out in front of his, shielding her, despite looking as though she were still processing something that was amiss. Emma noticed and smirked at him.

"How's the wife, Logan? I hear congratulations are in order. I can hardly believe it. Do you think it's a boy or a girl?"

His eyes narrowed and his rage increased a few levels. Emma always knew too much. Every time they saw her she said something that indicated insider information. How had he not seen that sooner? _This had to stop_. These people would never torture Lucy or himself again. He wouldn't allow it. He shoved Emma away and lunged for her discarded gun.

"No, Wyatt!"

He knew what would happen next. He could hear it in Lucy's voice. He waited for burning feeling of the knife piercing his side but it never came. A gunshot rang out instead. He picked up Emma's gun and spun around to find older Lucy standing over Emma's lifeless body with a glare that intended to kill faster than any bullet.

"Not this time," she muttered as she held his weapon in a steady grip, still leveled at Emma. "Not _him_."

His Lucy's eyes widened and found his. He saw confusion and dread and relief and wondered how it was possible for one pair of eyes to tell him so much. He crossed the distance to her quickly, well aware that he had to step over two bodies to reach her. His hand was under her chin as soon as he was close, inspecting her face with a worried a gaze.

"Are you hurt anywhere else? What happened?" He asked as he pulled her as close to him as he could and searched her face for answers. Her eyes left his to look over his shoulder. She was either looking at herself from the future or her dead mother. God, their lives were fucked up if those were the options. "Lucy? Look at me. Please."

She pulled her watery, and red eyes to his as if it were the hardest thing she would ever have to do and he knew then she'd been staring at her mother.

"Are you hurt anywhere else?"

He needed to know if there was anything urgent. Anything that he needed to address _now_. Hearing her speak would also assure him she wasn't going into shock.

She struggled to breathe and hissed through some kind of pain. "My—my ribs. And my throat." Her voice was hoarse and quiet and that's when he realized the yell he heard earlier didn't come from his Lucy. "My mother, Wyatt, she…she jumped in front of Emma's gun for me. Emma shot her for it." The pain in her voice and the disbelief in her eyes made him want to hold her and never let go. A second later her face crumpled and she collapsed against him with a gut wrenching sob. He leaned them against the brick wall of the nearest building as her full weight fell against him and pressed kisses to the top of her head. _Goddamnit_ , would they ever stop losing?

The older Lucy approached and pressed his gun and a letter into one of his hands. She gave him a wan smile and spoke over Lucy's tears.

"She'll ask about me later," Lucy told him. "She'll ask about a lot of things later. When she does, give her that letter. Things are going to look pretty bleak for a while, but the letter should give her hope."

"Where are you going?" Wyatt asked.

She thought about her answer and then smirked at him. "Back to the future."

He closed his eyes at the joke and let out a huff of a chuckle. Not a full chuckle, he was too worried about the woman sobbing into his neck for that, but he could appreciate the joke.

She continued with an almost wistful smile. "And hopefully back to _you_." Her eyes drifted to the back of Lucy's head and then came to meet his with a scolding glare. "Don't waste time. You pass, time doesn't. Don't let yourself pass any longer without _telling her_. I know words aren't your strong suit, Logan. But _use them_. She needs to know. _Tell her everything_ and you'll find your way back to each other, eventually."

"You sure about that?" He asked with his own tearful gaze. He was terrified he had broken them beyond repair.

"She never stopped loving you," Future Lucy said with a confident nod. "Not for a moment. Trust the source."

"I hope he's waiting for you when you get home," Wyatt told her with a soft smile. He could feel his eyes watering as the older Lucy turned to walk away from him. This was too much. He had two heartbroken Lucys to deal with and both of them were at least partially scarred because of him.

She stopped at the edge of the alley and glanced over her shoulder at him. "You will be. I have no doubt."

And then she was gone. Probably headed to her time machine and to her present. It should have seemed impossible to him, two Lucy's in one place, because that's what they had been told from the very beginning. But for some reason, he never questioned it. Lucy, in any time, would find a way to save the people she loved. She would figure it out.

He would have to do that too. But he couldn't do it without her. She was still crying against him as he ran his hands through her matted hair and kissed the top of her head.

"I'm sorry, Lucy," he whispered. He was sorry for hurting her as much as he did over the last few weeks, sorry for the now-alternate timeline where he hurt the future version of her, sorry that she just lost yet another person she loved. Just... _sorry_.

She pulled back to look at him and sniffled. Her cheeks were soaking wet and covered with dirt and blood. He wanted to run away with her and hide her from the world so nothing could ever hurt her again.

"Was that...was that _me_?" She asked.

He nodded. "Yes, ma'am."

"Did she tell you _when_ she from?"

"No, ma'am."

"How were the two of us able to be in the same place at once?"

He gave her a small amused smirk before answering. "No idea, ma'am."

Her eyes narrowed at him as she realized what he was doing, what moment he was recreating. Her pursed lips gave way to a weak grin. "I see you, Wyatt Logan."

He chuckled at her and shook his head as he feigned innocence. "I have no idea what you're talking about."

She gave him an amused glance and then asked, "Seriously, what was she doing here?"

"What Lucy Preston is always doing."

"And what's that?" She asked him with a furrowed brow.

"Saving my life," he answered as he held her gaze for a long moment. "And once again, I probably didn't deserve it."

He brought a hand up to her quickly bruising eye and carefully ran the backs of his fingers across the sensitive skin.

"And I definitely don't deserve _you_ ," he told her before offering her a bitter lop-sided grin. "Don't see how I ever could."

"Wyatt… **.** "

She looked panicked and tense. He didn't blame her. This wasn't the time or place. "Don't worry. I'm not trying to start this talk here and now," he assured her. "But the minute we land in the bunker there are things you need to hear - things you need to know. I put it off, I fought it, I flat out lied to myself, and I can't do that anymore."

She swallowed thickly and nodded. "Okay, when we get back. We'll talk."

For a moment, she looked ready to say or ask something else but that moment immediately passed at the sound of frantic voices calling for them.

"Guys!"

Lucy stepped out of his arms and they both turned to find Rufus, Jiya, and Flynn. Rufus was leaning heavily on Jiya as they hobbled forward and Flynn was cradling his arm against his chest. They all looked as if they'd been tossed around pretty good.

"We saw Future Jiya!" Rufus yelled excitedly as they approached.

Jiya looked pale and dazed as she shook her head. "I looked so...so _emo_. Like 80s sci fi movie heroine emo. Full Ripley or Sarah Connor. Black tank top, black cargo pants, short curly hair. Who _let_ me do that?"

Flynn rolled his eyes and huffed before turning to look at Lucy, and only Lucy, which left Wyatt with the urge to punch him. He didn't, though, because despite everything Garcia Flynn was there for Lucy while Wyatt was an ass. That earned him a small amount of gratitude.

"The point being, she told us where to find the Mothership," Flynn informed them.

"And saved my ass from a bullet to the chest," Rufus said as he leaned further into Jiya and pressed a kiss to her temple. "Thank you in advance."

"You're welcome in advance," Jiya said with a soft smile. "Now, we can all go home, Agent Christopher can _Raiders of the Lost Ark_ both time machines, and Rittenhouse can't change history. Not anymore."

"After we right a few wrongs," Wyatt told them. "We have a few people to save first."

Flynn peered at Wyatt suspiciously. "Do you mean—"

"You helped us, now we help you," Wyatt said with a deep breath and a nod.

He still wasn't over all the times Flynn had tried to kill them, all the wrong he had done, but after the way Wyatt had fucked up over the last few weeks he could understand Flynn a _little_ better. He could see how easy it would have been for _him_ to end up on Flynn's path.

"And Amy," Wyatt said as he turned to Lucy. "Her too."

Lucy shook her head. "Wyatt, we don't even know what Emma and...my mother...did. We may not be able to get her back at all."

"We _will_ ," he promised. "We'll figure it out. If anyone deserves a win it's you, Lucy. We'll find a way."

Together. They would find a way _together_. He still held the older Lucy's letter in his hand. Her words came back to him then. _Things are going to look pretty bleak for a while, but the letter should give her hope_.

They could all use a good dose of hope right now.

He held the letter out to Lucy. " _She_ left this for you."

Lucy gave him a startled look and took the letter from him with a trembling hand. She unfolded it and began to read. No sooner had she read the first line before she was gasping and smiling brightly. She placed a steadying hand on his arm as she turned the letter toward him so he could see.

" _Amy_ , Wyatt, she's telling me how to save Amy!"

In her excitement she didn't see the post script at the bottom of the letter. But he did. If seeing his Lucy smile like she was now wasn't enough to lift his spirits and make him excited for the future then the post script would have definitely done that all on its own.

 _PS - Loving him hurts right now. I know. I'm the only one who really knows. But don't give up on him. Let him make it up to you. Let him love you. Let him try. I lived through a life where he never had that chance. Where you never really knew how he felt. That life hurt worse than loving him ever did. Let. Him. Love. You. Let him help you grow. Heal each other. Save each other. If I know the both of you like I think I do then it will never be easy, never be perfect, but it will always be a necessity. He will always be an invariant necessity. Unchanging. Constant. Invariant. You love him so fight for him, even if you're fighting your own fears. Even if you're fighting his fears. Even if you're fighting him. Do whatever you have to do, just don't let him go. Now that you have him back. Never let him go._


End file.
